Comedian and Academy Award-winning actor Robin Williams was found dead in his Northern California home on Monday, local authorities said. He is remembered for his zany comic persona as well as more subtle dramatic performances. Photo: AP

Robin Williams, who died Monday at age 63, harnessed his zany comic persona to become one of Hollywood’s most celebrated and bankable movie stars.

Mr. Williams was found dead at his home in Tiburon, Calif., just north of San Francisco, according to the Marin County Sheriff’s Office.

The apparent cause of death was suicide by asphyxiation, although an investigation is continuing.

Marin County Sheriff’s Office Statement

Emergency personnel found Mr. Williams inside the house he shared with his wife, Susan Schneider, after a 911 call reported a man unconscious and not breathing. The sheriff’s office said Mr. Williams was last seen alive at 10 p.m. on Sunday.

Mr. Williams’s high energy at times masked a personal struggle with alcohol and drug addiction, and a representative for the actor said Monday that “he has been battling severe depression of late.”

After starting his career in stand-up comedy and bursting into public consciousness in 1978 with the hit television comedy “Mork & Mindy,” Mr. Williams built an acting career that included a mix of over-the-top star vehicles like “Mrs. Doubtfire” and “The Birdcage,” along with well-received roles in dramas including “Awakenings” and “Insomnia.”

He was nominated for four Oscars, winning best supporting actor for his role as a therapist to a troubled young math genius in “Good Will Hunting,” which was released in 1997. “This might be the one time I’m speechless,” he said upon accepting the award.

Since his days on “Mork & Mindy,” a fish-out-of-water tale that ran for four seasons in which he played an alien from the planet Ork, Mr. Williams demonstrated a fully formed comedic style filled with tics and habits that would become his trademarks.

Those idiosyncrasies, like monologues full of non sequiturs or unexpected accents, would help him quickly become one of the world’s biggest comedy stars and a favorite guest of late-night television talk shows. Even when not pictured on screen, Mr. Williams had a tendency to become the center of attention, including a celebrated turn as the voice of the madcap genie in the 1992 animated film “Aladdin.”

In 1986, he worked with fellow comedians Whoopi Goldberg and Billy Crystal to start Comic Relief Inc., a charity that raises money for the homeless. Together, they hosted an annual comedy fundraiser for more than a decade, reuniting in 2006 to raise money for people displaced by Hurricane Katrina.

Robin Williams speaks onstage during the Emmy Awards last September in Los Angeles. Kevin Winter/Getty Images

But Mr. Williams surprised many fans who thought of him as “Mork from Ork” by harnessing his manic energy into a string of more dramatic roles. Beginning with 1987’s “Good Morning, Vietnam,” he was nominated for a best actor Oscar three times in five years, with nominations also for “Dead Poets Society” and “The Fisher King.”

Mr. Williams’s acting career slowed in the past decade. He starred in the short-lived series “The Crazy Ones,” which was canceled in May. He recently played the role of Teddy Roosevelt in the family comedy “Night at the Museum: Secret of the Tomb,” which will be released in December.

“As he is remembered, it is our hope the focus will not be on Robin’s death, but on the countless moments of joy and laughter he gave to millions,” said Ms. Schneider, his wife.